Planetscale

PlanetScale Database Development Playbook

This skill enforces strict production-grade standards for relational database development (MySQL, PostgreSQL, serverless DBs), index design, schema branching, and migration workflows.

Target Triggers

• /planetscale
• "database branch"
• "optimize database query"
• "database index design"

Operational Standards

1. Schema Branching Workflow

• Never perform direct DDL modifications or raw schema migrations on the main/production database.
• Always perform database migrations on a dedicated schema branch (e.g. db branch create feature-name).
• Once migrations are fully validated in the dev environment, generate a deploy request (similar to a pull request for schemas).

2. Query Performance & Indexing

• Avoid database table scans. Ensure queries utilize a defined index.
• Run EXPLAIN or query plan analyzer on critical query layouts to check for index hit rates and scanned rows.
• Ensure foreign keys (or logical relationships in serverless DBs) have corresponding indexes on the referencing side to prevent slow join times.

3. Preventing N+1 Query Loops

• Audit route handlers and services for database queries executed inside loops (e.g., fetching a list of records and executing a query for each row).
• Replace nested loops with batch selections (using IN clauses) or proper database joins.

4. Online Schema Migrations

• Write migrations so that they are backward-compatible with running application versions (avoid renaming columns or dropping active tables directly).
• For column additions, provide nullable types or default constraints to prevent application crashes during zero-downtime deployment.